This is an open-label, multi-center, randomized, two-arm parallel, no-treatment group controlled (only for the first 6 months), Phase 3 study in children with ISS. The subjects will be treated with 0.067 milligram/kilogram/day (mg/kg/day) of Saizen®, weight base dose, for 12 months (12 months of treatment in the test group, and 6 months of no treatment and then 6 months of treatment in the control group).